Feature/issue 3 creating simple state

Implementation of simple state, and views of menu state & opts blocks (no functionality).
How does this check work? If it looks up the output value of the plugged in block, maybe the `Choice` block should be setting its output value?

I think this might actually be something we could test. Something like:

```javascript
describe("MenuState", function() {
  describe("input:CHOICES", function() {
    it("should only accept Choice blocks");
  });

  describe("input:OPTS", function() {
    it("should only accept option blocks");
  });
});
```

Maybe its overkill though. What do you think?